Presentation engine¶

What is a Presentation engine

A Presentation engine object is required to create the user interface of a Q Application at runtime. This creates the user interface beginning from a startup window set in the project (see Window) and presents the graphical elements in the formatting set in the individual objects and/or in the selected style sheet (see Stylesheets).

Two types of Presentation engines are available:

Native presentation engine Native presentation engine, which integrates the UNIQO Native presentation engine in Q Applications.
Web presentation engine, to be used when the Q Application user interface is displayed via a web browser.

Native presentation engine

This Presentation engine is used for typical HMI applications to run on targets equipped with an operator panel. There can be at most one in a project.

When the project starts at runtime, it automatically generates an interactive session (see Sessions and locale) initially authenticated with the user specified in the Starting user property. In the same interactive session it is possible to change user. Based on the user and the logics created, the interface in the same session can change dynamically (to design the user change in Q Studio, see Global Methods: User; to do it with C#, see Session activity log and audit).

Web presentation engine

This Presentation engine is used for both typical HMI applications to run on targets equipped with an operator panel and for blind devices, when we want to make available a web user interface to which multiple users can connect from different web browsers. There can be one of them at most in a project.

When a client connects to the web server, the object generates an interactive session (see Sessions and locale) for the authenticated user. The same user can access the project from multiple devices, and for each the object generates an additional interactive session. In each session the set start window is created.